This invention relates generally to cable tray systems used to support electrical wiring, cables, conduit, and data transmission lines (collectively “cables”), and more particularly to a cable tray supported by rigid side rails.
Cable trays systems generally provide support for cables as the cables extend from a first location to a second location. The conventional cable tray system is made up of a large number of trays positioned end to end along a desired route where cables are to be placed and supported. The cable trays, in turn, are supported by a number of brackets or hangers mounted on support shafts (such as sub-floor support shafts holding up a raised floor), walls, ceilings, floors or other building structures. The trays are connected to each other by clips or clamps.
There are many different kinds of cable trays, some for lighter duty applications and some are for heavier duty applications. As may be expected, the heavier duty trays are typically more expensive to manufacture and may also be more difficult to assemble. Some common types of cable trays include wire basket cable trays, pan trays, ventilated trough trays, ladder trays, and solid bottom trays. Wire basket cable trays include interconnected members such as metal bars or wires. Most basket cable trays include space apart U-shaped cross members which are connected by lateral support members along the sides and bottom of the tray. The cross members are generally perpendicular to the longitudinal axis of the cable tray. The cables are generally supported by the bottom portion of the cross members as the cable tray system carries the cable from one point to another. Basket cable trays are relatively inexpensive, however, they do not support as much weight as other types of cable trays.
Another type of cable tray is called a ladder-type cable tray. A ladder-type tray comprises a pair of parallel side rails and a series of spaced-apart rungs extending between the rails, the rails and rungs are typically made from a metal such as aluminum or steel. The rails are usually secured to the rungs by welding. Welding, however, has certain disadvantages, including inconsistencies in the weld joints, the creation of noxious fumes, the need for protective equipment, high labor and capital costs, a relatively low production rate, and the need to clean the parts after the welding is complete. A ladder-type tray is much sturdier than a basket cable tray, however, it is usually much more expensive to manufacture and more difficult to assemble. Further, these types of trays are usually assembled before they are shipped to the jobsite. The fully assembled trays do not pack together tightly making them difficult and expensive to ship.
There is therefore a need in the art for a cable tray apparatus which overcomes these and other deficiencies in the prior art.